NCEDC Blog

The NCEDC revamped its Web pages this month, with the goal of making the data center easier to use! In addition to updating the look of the Web pages, we have provided new and addition information about the holdings of the data center and added the capability to search the Web pages.

As part of this effort, some pages were renamed and others were removed. If you are having problems finding something, please let us know! And feel free to make any comments on the layout or organization of these Web pages.
The NCEDC is a joint project of the University of California, Berkeley and the USGS. Please send us email at ncedcinfo@ncedc.org or fill out our comments form.

The USGS Northern California Seismic Network (NCSN) has recorded seismic waveforms for events in northern California from 1984 through present time. These data are archived at the NCEDC, and are now available to users via the EVT_FAST automated event waveform retrieval system through web and email requests. The EVT_FAST system allows users to request all of the waveforms for a specified NCSN event with a simple one-line request. Users can request event waveform data in one of the following formats:

SAC binary

SAC ascii

AH (XDR)

The NCEDC is committed to distributing all waveform data and corresponding instrument response data in the standard SEED format, and is actively working with the USGS to assemble the required instrument response data for the NCSN waveforms. Until the instrument response meta-data is available, the EVT_FAST system provides a quick and easy way for users to acquire NCSN waveform data.

The SeismiQuery program, a web-based program developed by the IRIS DMC, is now available the NCEDC. SeismiQuery provides users with a variety of pre-formatted queries concerning waveform data, instrument response, and channel information database from the NCEDC using easy point-and-click or forms-based requests.

Although the name SeismiQuery may imply seismic data, the program provides information about all waveform and related channel information and responses for any data in the NCEDC database. This include broadband and strong motion waveform data from:

The Northern California Earthquake Data Center (NCEDC) and the U.S. Geological Survey (USGS) are pleased to announce the availablity of extensive "low frequency" geophysical and fault monitoring data.

With National Earthquake Hazards Program (NEHRP) funding, the USGS has supported various fault monitoring efforts. In addition to monitoring at seismic frequency bands, the USGS also has supported strain, creep, water level and other instrumental systems operating at "low frequency". Principal investigators include both USGS and academic scientists. The typical observation interval for these data sets is 10 minutes (0.00167 hz).

Raw data from most of these instruments are now available at the NCEDC, and are archived with the FDSN assigned network code "UL". The "SeismiQuery" web interface, initially developed by IRIS, can be used at the NCEDC to query the inventory and responses for this data. The raw low frequency data can be accessed with seismic querying tools such as NETDC and BREQ_FAST, and NCEDC web forms, and are are retrieved in SEED format, a standard format adopted for seismic data. The NCEDC raw data archive for this network consists of data from 1974 to the present, contains over 800 channels of data, and includes over 354 active data channels that are updated on a daily basis.

In a companion effort, the USGS is providing access to preliminary cleaned versions of these data that have been automatically scaled and modified to remove offsets and telemetry glitches. No checking of these data or the parameters used to generate them is currently being done. Careful review of the data should be done before any scientific conclusions can be drawn. The data do however provide a starting point for general viewing of fault behavior. The cleaned time series are available as plots (most recent week, most recent month, most recent year, and complete time series) and as downloadable files in either a tabular format or as an eXtensible Markup Language (XML) file.